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CHAPTER 17. Environmental Hazards and Human Health. An introduction to hazards and human health. The highly virulent H5N1 avian flu first appeared in 1997 Infecting poultry, other birds, and humans Hundreds of millions of poultry have been slaughtered

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Chapter 17

CHAPTER 17

Environmental Hazards and Human Health


An introduction to hazards and human health
An introduction to hazards and human health

  • The highly virulent H5N1 avian flu first appeared in 1997

    • Infecting poultry, other birds, and humans

    • Hundreds of millions of poultry have been slaughtered

  • The 2009 H1N1 swine flu outbreak spread rapidly

    • The World Health Organization declared a global influenza pandemic

  • 39 new diseases have spread from animals to humans

    • SARS, the Ebola virus, West Nile virus, hantavirus

    • New diseases will appear as we change the environment


The old enemies
The old enemies

  • The new, emerging diseases are not our greatest threat

  • The common, familiar ones take the greatest toll

    • Malaria, diarrhea, respiratory viruses, worms

    • Especially in developing countries

  • In developed countries, cancer is the killer most closely linked to the environment

    • Due to our exposure to chemicals

  • Environmental health: connections between environmental hazards and human disease and death


Links between the environment and health
Links between the environment and health

  • Pollution: the presence of a substance in the environment that because of its composition or quantity prevents functioning of natural processes and produces undesirable environmental or health effects

  • Pollutant: any material that causes pollution

    • Usually by-products of some desirable action

    • Agriculture, comfortable homes, transportation, etc.

  • Pollution has increased due to population and consumption

    • Along with accumulation of nonbiodegradable products (e.g., plastic, synthetic organic chemicals)



Pollution is everywhere
Pollution is everywhere

  • Any part of the environment can be polluted

    • Almost anything can be a pollutant

  • The only criterion? The addition of a pollutant results in undesirable changes

  • Impacts can be:

    • Aesthetic: hazy air, litter

    • On ecosystems: fish or forest die-offs

    • On human health: water contaminated with waste

    • Local (a contaminated well) or global (ozone depletion)

    • Too much of a natural compound (e.g., fertilizer)


Our existence necessitates waste production
Our existence necessitates waste production

  • So…we need to…

  • Identify the material(s) causing the pollution

  • Identify the source(s) of the pollutants

  • Clean up the environment

  • Prevent pollutants from entering the environment

  • Avoid the pollution altogether

  • Transitioning to a sustainable society will require a technology transition from pollution-intensive to environmentally friendly processes


Environmental health
Environmental health

  • Environment: the whole context of human life

    • The physical, chemical, and biological setting of where and how people live

    • Home, air, water, food, workplace, climate, etc.

  • Hazard: anything that can cause:

    • Injury, disease, death to humans

    • Damage to personal or public property

    • Deterioration or destruction of environmental parts


Hazards risk and vulnerability
Hazards, risk, and vulnerability

  • Undesirable consequences do not necessarily follow a hazard

  • Risk: the probability of suffering injury, disease, death, or some loss as a result of exposure to a hazard

  • Vulnerability: some people (e.g., the poor) are more vulnerable to certain risks

  • Risk = Hazard x Vulnerability

  • The presence of avian flu in poultry: a hazard that presents the risk of humans getting the disease

    • People working with poultry are more vulnerable


Dose response and threshold
Dose response and threshold

  • The dose (level of exposure multiplied by the length of time of exposure) is linked with the response (effects)

    • If a chemical has a low toxicity, concern centers on chronic or carcinogenic effects

  • Human exposure to a hazard is a vital part of risk characterization

    • Exposure comes from the workplace, food, water, and environment

    • It is hard to get an accurate determination of exposure


Threshold level
Threshold level

  • There is usually a threshold level in the dose-response relationship

    • Organisms can usually deal with some level of a substance without suffering ill effects

  • Threshold level: the level below which there are no ill effects

    • Effects above this level depend on concentration and duration of exposure

    • It is high for short exposures, and lower as time increases



Threshold levels for carcinogens
Threshold levels for carcinogens

  • The EPA takes a zero-dose, zero-response approach for carcinogens

    • There is no evidence of a threshold level for them

    • But lower doses are less likely to produce cancers

  • The field of toxicology is well established

    • It is the most important source of sound science for supporting regulations from the EPA and FDA

  • The NTP was established in 1978

    • The world’s leader in assessing chemical toxicity and carcinogenicity


The picture of health
The picture of health

  • Health: a state of complete physical, social, and mental well-being

    • Not just the absence of disease or infirmity

  • Environmental health focuses on disease

    • Health: the absence of disease

  • Two measures are used to study disease

    • Morbidity: the incidence of disease in a population

    • Mortality: the incidence of death in a population

  • Epidemiology: the study of the presence, distribution, and prevention of disease in populations


Infectious diseases
Infectious Diseases

  • http://www.nbclearn.com/portal/site/learn/changing-planet


Public health
Public health

  • Federal government

    • Centers for Disease Control and Prevention (CDC)

      • Provides tools and information to protect health

      • Involved in health risk management and prevention

  • Each state has its own public-health agency

    • Can require shots, quarantines, monitoring diseases, etc.

  • The U.S. has a huge health care industry

    • Medicare, Medicaid, hospitals, physicians, etc.


Other countries
Other countries

  • Most countries have a ministry of health that acts on behalf of its people to manage and minimize health risks

  • Health policies are limited by information and funding

    • Limited funds should go to strategies that achieve the greatest risk prevention

  • Countries have access to the WHO

    • Established by the UN in 1948

    • Everyone should get the highest possible level of health

    • Staffed by professionals and governed by the World Health Assembly


Life expectancy
Life expectancy

  • A universal indicator of health

    • In 1955, it was 48 years

    • It is now 68 years and will rise to 73 by 2025

  • Longer lives: due to social, medical, economic advances

  • Epidemiologic transition: decreasing death rates accompany development

    • Infectious diseases are replaced by diseases of aging

    • But 92 million children still die each year

    • Common diseases kill 47% of people in poor countries

  • Industry and intensive agriculture have their own hazards


Environmental hazards
Environmental hazards

  • Four classes of environmental hazards:

    • Cultural, biological, physical, chemical

  • There are two ways to consider hazards to health

    • Lack of access to resources (clean water, food)

    • Exposure to hazards in the environment that brings risk of injury, disease, or death

  • Cultural hazards: many factors that cause death or disability are a matter of choice

    • People engage in risky behavior (smoking, drinking, drugs, don’t exercise, risky sexual practices, etc.)


Biological hazards tuberculosis malaria and parasites
Biological Hazards: Tuberculosis, malaria, and parasites

  • Mycobacterium tuberculosis infects one-third of all people

    • Tuberculosis has resurged due to complacency, HIV-weakened immune systems, and drug-resistant strains

  • Malaria kills 881,000 people each year

    • A mosquito infects a person with a protozoan parasite

    • Red blood cells are destroyed, leading to anemia, fever, chills, and malaise

  • 3.5 billion people suffer from parasitic worms

    • Hookworms and schistosomes


Physical factors in harm s way
Physical Factors: In harm’s way

  • Hurricanes, earthquakes, volcanoes, etc

  • Much loss from natural disasters is due to poor environmental stewardship

    • Deforested hillsides

    • Building on floodplains, below volcanoes, on geologic faults, marshes, and mangrove forests

  • People assume disasters happen to other people

  • Stupid zones could be created for areas that shouldn’t be built

    • Areas prone to hurricanes, earthquakes, volcanoes, etc.


Chemical hazards
Chemical hazards

  • Industrialization has resulted in technologies that use chemicals

    • Cleaning agents, pesticides, fuels, medicines, paints, etc.

  • Exposure is through ingestion, breathing, the skin, direct use, or by accident

  • Toxicity: condition of being harmful, deadly, or poisonous

    • Depends on exposure and dose (the amount absorbed)

  • Different people have different thresholds of toxicity

    • Children and embryos are most sensitive



Carcinogens
Carcinogens

  • Many chemicals are hazardous even at very low levels

    • Heavy metals, organic solvents, pesticides

  • Acute poisoning episodes are understandable and preventable

    • But it is hard to determine effects of long-term exposure to low levels of substances

  • Carcinogens: cancer-causing agents

    • Cancer develops over decades, so it is hard to connect cause with the effect

    • There are 51 known and 188 suspected carcinogens

  • Developing nations have rising exposure to chemicals


Pathways of risk
Pathways of risk

  • What pathways lead from risks (of infection), exposure (to chemicals), and vulnerability (to hazards) to human deaths?

  • A very small number of risk factors cause the vast majority of premature deaths and disease

  • One major pathway for hazards: poverty

    • The world’s biggest killer in both developing and developed nations

    • People lack access to health care, clean water, nutritious food, healthy air, sanitation, and shelter




Priorities
Priorities

  • Education, nutrition, and wealth do not explain everything

  • A nation may make deliberate policy choices to improve the health of its population

    • Instead of militarization or power sources

  • Costa Rica, China, and Sri Lanka have longer life expectancies and lower infant mortality than expected

    • They focused public resources on immunization, upgrading sewer and water systems, and land reform



Marlboro country
Marlboro country?

  • Tobacco is the only product sold that kills half its users

  • It is clearly correlated with cancer and other lung diseases

    • It is responsible for 29% of U.S. cancer deaths

    • 5.4 million die worldwide each year

  • Synergistic effects: smokers living in polluted air or working with asbestos have higher rates of lung cancer

    • Black lung disease occurs mainly in smokers

  • Smoking costs the U.S. $193 billion/yr in health care costs and lost job productivity


Decreasing tobacco use
Decreasing tobacco use

  • Raising taxes: the most effective measure to reduce tobacco use

    • Providing billions of dollars to state and federal governments

  • Other measures to reduce smoking include warnings, smoke-free workplaces, non-smoking areas, and banning smoking on domestic flights

    • The U.S. smoking population dropped from 42% to 19.8% since warnings began


Secondhand smoke
Secondhand smoke

  • In 1999 the EPA classified environmental tobacco smoke (ETS), secondhand smoke, as a Class A (known) carcinogen

    • A serious and substantial public health risk

    • Specific steps now protect children in public places

  • The Occupational Safety and Health Administration is working to protect workers from ETS

  • In 1999, Congress gave the Food and Drug Administration sweeping power to regulate tobacco

    • Overcoming efforts of the powerful tobacco lobby


Legally speaking
Legally speaking

  • The attorneys general of several states sued tobacco companies

    • In 1998, 46 states reached a $246 billion settlement

  • Tobacco companies would reimburse states for smoking-related illnesses

    • Help finance programs to discourage smoking

  • Other lawsuits have not been successful

    • Judges ruled that earlier court rulings forbade them from imposing fines


Risk and infectious diseases
Risk and infectious diseases

  • Epidemiology is “medical ecology”

    • Epidemiologists trace a disease’s location, transmission, and consequences

  • Infectious diseases and parasites are more common in developing countries

    • Inadequate hygiene, inferior sewage treatment

    • A lack of resources for public-health infrastructure

  • Developed nations also have outbreaks of diseases

    • In 1993 Milwaukee’s (Wisconsin) water supply was contaminated by animal wastes, hospitalizing over 4,000


Tropical diseases
Tropical diseases

  • The tropics have ideal climates for insect-borne diseases

  • Mosquitoes are vectors for yellow fever, dengue fever, elephantiasis, Japanese encephalitis, West Nile, malaria

    • Malaria is the most serious

  • Control of malaria focuses on vector control: using pesticides on the Anopheles mosquito

    • Or treatment strategies: curing infected people

    • Malaria has been eradicated in the U.S.

  • DDT is a successful, yet controversial, control for mosquitoes in developing countries



Net results
Net results

  • Giving children insecticide-treated nets over their beds reduces mortality from all causes

  • Bed nets, indoor DDT spraying, and effective drugs reduce malaria deaths

    • A cost-effective, large-scale intervention in Africa

  • The Plasmodium protozoan is becoming resistant to drugs

    • Chloroquine is now ineffective against malaria

  • ACT (artemisinin combination therapy) is effective

    • But resistance is appearing



Toxic risk pathways
Toxic risk pathways

  • Airborne pollutants are hard-to-control hazards

    • Hard to measure and avoid

  • Three categories of impacts

    • Chronic: pollutants cause gradual deterioration of physiological functioning over years

    • Acute: pollutants cause life-threatening reactions within hours or days

    • Carcinogenic: pollutants cause cellular changes leading to uncontrolled growth and division (cancer)


Developing countries
Developing countries

  • Developing nations have the most serious threat

  • Three billion use wood or dung for cooking and heating

  • Fireplaces, stoves, etc. are not properly ventilated

    • Exposing people to carbon monoxide, nitrogen and sulfur oxides, soot, benzene (a carcinogen)

  • Problems associated with indoor cooking: acute respiratory infections, chronic lung disease (asthma, bronchitis), lung cancer, birth defects

  • Solutions? Ventilated, efficient stoves

    • Using bottled gas or liquid fuels instead of biofuels


Hazard assessment is this really a hazard
Hazard assessment: is this really a hazard?

  • Hazard assessment: the process of examining evidence

    • Linking a potential hazard to its harmful effects

    • Historical data are often used to calculate risks

  • A link may not be clear due to a time delay between exposure and effect

    • An epidemiological study tracks how a sickness spreads

    • Are people exposed to a hazard sicker than the unexposed?

  • Animal testing: uses animals to determine what might happen

    • Uses hundreds of animals (mice) over years at high costs



Objections to animal testing
Objections to animal testing

  • Rodents and humans may have different responses to a chemical

  • Doses given to animals are much higher than humans are exposed to

  • Some people are opposed for ethical reasons

  • All chemicals shown to be human carcinogens are also carcinogenic in test animals


Just test people
Just test people?

  • Chemical manufacturers used to pay people to test products

    • They are less expensive than animal testing

  • A National Academy of Sciences panel stated this was unjustifiable

    • The EPA banned such tests

    • The Bush administration pressed to allow testing

  • A 2006 EPA ruling allowed testing to restart

    • But forbids testing on children or pregnant women

    • The Natural Resources Defense Council is suing

    • The Obama administration may stop this testing


The precautionary principle
The precautionary principle

  • The precautionary principle: where an activity threatens harm to humans or the environment, precautionary measures should be taken even if some cause-and-effect relationships are not fully known

    • Proponents of the activity, not the public, should bear the burden of proof


Using the precautionary principle
Using the precautionary principle

  • It is well-established in Europe

    • It is the basis for environmental laws

  • It overlies some U.S. policies

    • Pharmaceuticals and pesticides

  • A substance is presumed guilty until proven innocent

    • It is not permitted until tests prove it is safe

  • It can implement stewardship in environmental health

    • But should not be a blanket policy

    • It can counter pressures from proponents

    • Use it where the penalty for being wrong is great


Chapter 171

CHAPTER 17

Environmental Hazards and Human Health

Active Lecture Questions


True or False: The existence of a hazard means that undesirable consequences will inevitably follow.

a. True

b. False

Review Question-1


True or False: The existence of a hazard means that undesirable consequences will inevitably follow.

a. True

b. False

Review Question-1 Answer


______ is the incidence of disease in a population, while ______ is the incidence of death in a population.

a. Mortality; morbidity

b. Morbidity; immortality

c. Morbidity; mortality

d. Immortality; mortality

Review Question-2


______ is the incidence of disease in a population, while ______ is the incidence of death in a population.

a. Mortality; morbidity

b. Morbidity; immortality

c. Morbidity; mortality

d. Immortality; mortality

Review Question-2 Answer


The infectious disease caused by protozoan parasites of the genus Plasmodium and propagated by mosquitoes in tropical areas is

a. tuberculosis.

b. HIV.

c. malaria.

d. rotavirus.

Review Question-3


The infectious disease caused by protozoan parasites of the genus Plasmodium and propagated by mosquitoes in tropical areas is

a. tuberculosis.

b. HIV.

c. malaria.

d. rotavirus.

Review Question-3 Answer


Which of the following is not a physical hazard a smoking b hurricanes c tornadoes d earthquakes

Which of the following is not a physical hazard? genus

a. smoking

b. hurricanes

c. tornadoes

d. earthquakes

Review Question-4


Which of the following is not a physical hazard a smoking b hurricanes c tornadoes d earthquakes1

Which of the following is not a physical hazard? genus

a. smoking

b. hurricanes

c. tornadoes

d. earthquakes

Review Question-4 Answer


Which of the following is a risk associated with being poor?

a. being underweight

b. unsafe sex

c. poor sanitation

d. all of the above

Review Question-5


Which of the following is a risk associated with being poor?

a. being underweight

b. unsafe sex

c. poor sanitation

d. all of the above

Review Question-5 Answer


According to Fig. 17-5, the continent most impacted by tuberculosis is

a. North America.

b. Asia.

c. Australia.

d. Africa.

Interpreting Graphs and Data-1


According to Fig. 17-5, the continent most impacted by tuberculosis is

a. North America.

b. Asia.

c. Australia.

d. Africa.

Interpreting Graphs and Data-1 Answer


According to Fig. 17-6, the number of days of lost life expectancy due to alcoholism is approximately

a. 1,000.

b. 2,000.

c. 3,000.

d. 4,000.

Interpreting Graphs and Data-2


According to Fig. 17-6, the number of days of lost life expectancy due to alcoholism is approximately

a. 1,000.

b. 2,000.

c. 3,000.

d. 4,000.

Interpreting Graphs and Data-2 Answer


The following is a statement of the ______ principle: “Where an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if cause-and-effect relationships are not fully established scientifically.”

a. causal

b. precautionary

c. measured

d. environmental

Thinking Environmentally-1


The following is a statement of the ______ principle: “Where an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if cause-and-effect relationships are not fully established scientifically.”

a. causal

b. precautionary

c. measured

d. environmental

Thinking Environmentally-1 Answer


All of the following are in the top 10 risk factors for developed countries except

a. tobacco use.

b. high blood pressure.

c. high cholesterol.

d. high fruit and vegetable intake.

Thinking Environmentally-2


All of the following are in the top 10 risk factors for developed countries except

a. tobacco use.

b. high blood pressure.

c. high cholesterol.

d. high fruit and vegetable intake.

Thinking Environmentally-2 Answer


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